Aluminum is a light weight, high strength and recyclable structural metal. It plays an important role in social progress and has a pivotal contribution in transportation, food and beverage packaging, infrastructure, building and construction, electronics and electrification, aerospace and defense. Therefore, the demand of aluminum is likely to increase with the growth rate of 4.1% per year.
The commercially mined aluminum ore is bauxite, it has the highest content of alumina along with mineral oxides of silica, iron, titanium, calcium, vanadium, manganese and other impurities in minor or trace amount.
The production of elemental aluminum from aluminum ore is basically an electrochemical process. It involves first chemical separation of alumina (aluminum oxide) from undesired components like oxides of iron, titanium, silica, calcium, vanadium, manganese etc. in bauxite and then electrolysis of alumina to obtain elemental aluminum.
The chemical separation of alumina generates enormous amounts of red mud waste or bauxite residue which is posing a very serious and alarming environmental problem. The electrolysis step in the production of aluminum uses aluminum fluoride and carbon anodes which lead to emission of perfluorocarbon gases (PFCs) and carbon dioxide respectively. Furthermore electrolysis of alumina requires large amount of electricity which expends over 12 KWh/Kg. Further there is consumption of the costly anode at a rate of about 0.4 ton/ton of aluminum. Therefore, the production of aluminum is expensive.
Several efforts have been made in the past to overcome one or more of the afore-mentioned drawbacks. Some of the examples of typical prior art processes for the manufacture of aluminum are disclosed herein below.
U.S. Pat. No. 4,308,113 discloses a process for manufacturing aluminum by using a modified graphite electrodes with reduced wear rates, wherein the modified graphite electrodes are prepared by titanium and/or aluminum compounds. These electrodes are used to control the ash content and also to decrease the cathode electrode wear in the electrolytic cell.
U.S. Pat. No. 4,396,482 discloses an electrolytic cell for production of metal such as aluminum. The composite cathode of the electrolytic cell comprises a base cathode and cathode extension surfaces made up of graphite and at least 90% refractory hard metal such as titanium diboride and a carbonaceous binder material.
U.S. Pat. No. 4,151,061 discloses a sealed-type electrolytic cell. This cell comprises aluminum chloride feeding port and chlorine gas discharging ports in a top section and a molten metal reservoir in a bottom section.
U.S. Pat. No. 3,725,222 discloses a continuous process for the production aluminum by electrolysis of aluminum chloride. In electrolysis cell used in said process contains aluminum chloride, dissolved in a molten solvent having a higher electro-decomposition potential than aluminum chloride.
U.S. Pat. No. 3,785,941 electrolytic cell for the production of aluminum by electrolysis of aluminum chloride is disclosed. The cell comprises an electrolytic chamber for holding a bath of molten metal chloride-based electrolyte, wherein the chamber has a non-conducting interfacial bounding for the bath or vapors and gases emanated from the bath. The non-conducting bounding is formed of a refractory material consisting essentially of nitride and/or oxide of silicon, boron or aluminum.
U.S. Pat. No. 4,252,774 is another prior art which discloses a method of manufacturing aluminum chloride from aluminous materials containing compounds of iron, titanium and silicon is disclosed. The method comprises reacting the aluminous materials with carbon and a chlorine-containing gas at a temperature of about 900° K to form a gaseous mixture, wherein the heated gases are passed in intimate contact with aluminium sulphide to precipitate out solid iron sulphide and form additional gaseous aluminium chloride and separating the gaseous aluminium chloride from the solid iron sulphide.
U.S. Pat. No. 4,039,648 is yet another prior art which discloses a method for manufacturing aluminum chloride by contacting Al2O3 with a reducing agent and chlorine in a bath of molten metal halides to form aluminum chloride and recovering the aluminum chloride by vaporization is disclosed.
Therefore inventors of the present disclosure envisaged a simple and economic process for obtaining metals from aluminum ore.